Annual Report on the External Quality Assessment Scheme for Clinical Parasitology in Korea (2017)

Annual proficiency surveys were conducted in March, May, and August of 2017 as the Korean Association of External Quality Assessment Service. Overall, four image samples (MPI-17-01, MPI-17-02, MPI-17-03, MPI-17-04) in the first trial, three image samples (MPI-17-05, MPI-17-06 , MPI-17-07) in the second trial, and a slide specimen (MPS-17-01) using parasite samples in the third trial were distributed to participating institutions. The first and second trial specimens were prepared by photographing slides made of formalin-ether concentrate of positive samples stored for educational purposes. The slide distributed in the third trial was prepared using cellophane tape, which was stored after diagnosis of the patients infected with Enterobius vermicularis . There were 191 participating institutions in the first, 204 in the second, and 212 in the third trial. The correct identification rates were 27.2% for MPI-17-01 Diphyllobothrium species (sp.), 96.6% for MPI-17-02 no parasite, 67.5% for MPI-17-03 Metagonimus yokogawai , 71.2% for MPI-17-04 Balantidium coli , 99.0% for MPI-17-05 Taenia sp., 99.0% for MPI-17-06 Trichuris trichiura , 92.7% for MPI-17-07 Cryptosporidium sp., and 96.7% for MPS-17-01 E. vermicularis . The current external quality assessment for clinical parasitology was performed using image samples and standard slides. Surveys of parasitic infections should be accompanied by continuous education on various parasitic infections, for which there was lack of experience of inspection in clinical laboratories. In the future, it will be necessary to establish a standard material using parasitic samples, and ultimately to conduct a survey on whole series of tests for the diagnosis of parasitic diseases.

Detection of Intestinal Parasites in Diarrhea Samples Using Various Diagnostic Methods and Evaluation of the Stability of In-house Quality Control Materials for Stool Examination

BACKGROUND: Because of a lack of quality control (QC) materials, stool examination has not been standardised. This study examined intestinal parasites in diarrhea specimens to manufacture and evaluate the performance stability of QC materials for stool examination. METHODS: This study examined diarrhea specimens submitted for stool culture. Microscopic examination was performed using the direct smear and formalin-ether concentration method (Military General Laboratory, MGL). Enzyme-linked immunosorbent assay (ELISA) kits (R-Biopharm AG, Germany) and xTAG Gastrointestinal Pathogen Panel (Luminex Corp., USA) were used for the three major protozoa: Cryptosporidium parvum, Giardia lamblia, and Entamoeba histolytica. Polymerase chain reaction (PCR) was performed for Dientamoeba fragilis and Blastocystis hominis. The QC materials for stool examination were generated using Diphyllobothrium nihonkaiense ova. The manufactured QC materials were evaluated under different storage conditions, with varying preservatives, temperatures, and storage times. RESULTS: From November 2015 to April 2016, 82 diarrhea specimens were collected and tested. All results from microscopy and ELISA were negative; C. parvum (n=2) and G. lamblia (n=1) were detected by xTAG, while D. fragilis (n=10) and B. hominis (n=2) were detected by PCR. High- and low-concentration QC materials were manufactured. Using the high-concentration QC material, ova were observed in all storage conditions using MGL. Using the low-concentration QC material, the ova were observed until 14 days, but not after 3 weeks. CONCLUSIONS: It should be considered for making QC materials for stool examinations that focus on D. fragilis and B. hominis frequently found in Korea and with the caution to the low-concentration of QC materials could be unstable.